This invention relates to the general use of solvents to separate unsaturated compounds (olefins, acetylenes, aromatics and carbon monoxide) from saturated hydrocarbons (paraffins or naphthenes), hydrogen, carbon dioxide, oxygen or nitrogen.
1,3-butadiene was commercially produced by solvent separation as long as forty years ago. (C. E. Morrell et al, Trans. Amer. Institute of Chem. Engs. 1946 pp 473-494). Carbon monoxide is produced commercially in a number of installations using a solvent of CuAlCl.sub.4 in toluene. (pages 788-93 of the Encyclopedia of Chemical Technology 3rd Edition vol. 4 and the references cited therein).
Many patents have been taken out which claim different solvents for the separation of olefins from various feedstreams. A number of patents claim a solution of CuAlCl.sub.4 in aromatics for this use.
A solution of CuAlCl.sub.4 in aromatics has many favorable characteristics for a separation solvent. Among these are heat stability, good heat and mass transfer rates along with a high solubility of olefins and acetylenes at relatively low pressure at ambient temperatures. In spite of the many good properties of CuAlCl.sub.4, no commercial acceptance has yet occurred for the separation of olefins and acetylenes. Intrinsic catalytic properties of CuAlCl.sub.4 (which may be largely prevented by the use of certain additives as reaction inhibitors) have so far prevented the successful commercialization of this technology. (D. G. Walker, Solid and Liquid Phases Containing CuAlCl.sub.4 Div. of Petroleum Chem. ACS 28 no. 3 746-55 Seattle March 1983).